Lung recruitment maneuver depresses central hemodynamics in patients following cardiac surgery

Objective To assess the impact of the lung recruitment maneuver on circulation following cardiac surgery.Design and setting Prospective randomized cross-over study at the Departments of Anesthesia and Thoracic Surgery, Copenhagen University Hospital.Patients Ten adult undergoing coronary artery bypass surgery.Interventions Patients were randomized to two durations of lung recruitment maneuvers (40 cmH₂O airway pressure for 10 s and 20 s or vice versa after 5 min) administered immediately after surgery.Measurements and results Transesophageal echocardiography (left ventricular short axis view), pulse contour cardiac output, and arterial blood pressure were monitored continuously. Systemic and pulmonary arterial blood gases were sampled before and after each lung recruitment maneuver to calculate the intrapulmonary shunt. Left ventricular end-diastolic areas decreased significantly during both the 10-s and the 20-s lung recruitment maneuvers. Cardiac output was 5.6±0.8 l/min at baseline, decreasing by 3.0±1.1 l/min and 3.6±1.2 l/min during lung recruitment maneuvers of 10 and 20 s, respectively. Shunt decreased from 20±5% to 15±6% after the first lung recruitment maneuver and from 15±6% to 12±5% after the second.Conclusions Lung recruitment maneuvers markedly reduced cardiac output and left ventricular end-diastolic areas in hemodynamically stable patients following cardiac surgery.This article is discussed by the editorial available at: Supported by the Danish Medical Research Council (no. 22-03-0299 and no. 22-04-0420) and the Danish Heart Foundation (no. 04-10-B152-A230-22194).